It seems more than appropriate to also cover redux-observable. It leverages ESNext observables with is significantly a better async abstraction than promises (inc. async/await) and callback-based systems.

It's also very popular to be used within React apps and redux will often also be used with libraries or frameworks that already leverage observables with significant gains over existing async abstractions such as RxJS & Angular 2 (which uses RxJS to provide observables be continuously available).

Thanks so much for your suggestion! In this course we opted to use redux-thunk for async actions since they're just functions. This means they're far easier to grok than observables or sagas, which are concepts that most JS developers aren't familiar with yet.

I do agree with the sentiment that it should be covered, I'm just not sure if this introductory course is the right place for that. Maybe this is something that could be covered in a more advanced Redux course, though!